Dendrimers are well defined globular molecules. These are generally prepared by stepwise or reiterative reaction of multifunctional monomers to obtain a branched structure. In U.S. Pat. No. 5,530,092, for example, the repetition of double Michael addition of acrylonitrile starting with a primary diamine followed by hydrogenation obtains two primary amines for each initial amine. This doubles the number of primary amine groups. Thus, beginning with a diamine, the first generation dendrimer (G1) has four primary amines; the second generation (G2) has eight primary amines; the third generation (G3) has sixteen primary amines; the fourth generation (G4) has thirty-two primary amines; the fifth generation (G5) has sixty-four primary amines in the outer shell, and so on. These polyamine dendrimers are said to be stable to degradation through hydrolysis reactions.
Amine-terminated polyamidoamine, polyethyleneimine and polypropyleneimine dendrimers are also known, for example, from U.S. Pat. Nos. 5,393,797; 5,393,795; 5,560,929; and 5,387,617, all to Hedstrand et al.
Polyisobutenyl succinimide-polyamidoamine dendrimer star-branched polymers obtained by reacting second generation polyamidoamine dendrimers with polyisobutenyl succinic anhydride are disclosed in Migdal's U.S. Pat. No. 4,938,885 [to Migdal]. These polymers are said to have dispersancy powers in lubricating oils and to exhibit antioxidant activity. However, these products are not hydrolytically stable.
U.S. Pat. No. 5,316,973 discloses telechelic olefin polymers such as telechelic diolefin polyisobutylene prepared by refluxing dihalogen polyisobutylene in tetrahydrofuran with a strong base such as potassium t-butoxide. This is said to produce a product which has .sup.1 H NMR spectroscopy at 60 MHz consistent with a terminal vinylene functionality of 2.0.
Boerzel et al., U.S. Pat. No. 4,152,499, discloses polyisobutylene said to contain a proportion of double bonds reactive with maleic anhydride of from 60 to 90 percent of the double bonds present in the polyisobutylene. The polyisobutylenes are prepared using a boron trifluoride polymerization initiator with a short polymerization time.
Bronstert et al., U.S. Pat. No. 4,599,433, discloses the preparation of polyisobutylene-succinic anhydrides with titanium, zirconium or vanadium alkoxides as catalysts which are said to isomerize polyisobutylene during the reaction making it more reactive with the maleic anhydride. The polyisobutylene-succinic anhydride adduct is in turn reacted with a polyamine to obtain a lubricating oil additive.